Voltage regulators



Feb. 15, 1966 B. K. NASTER 3,235,789

VOLTAGE REGULATORS Filed July 10, 1961 5 Sheets-Sheet 1 27G 22 Fig IREG. OUTPUT- L L25 INPUT I GD 51- F Pl 5| am +lQQJ M34 Ti Fla 2 84 46 8286 INPUT REG. OUTPUT INVENTOR. 50 BERT K. NASTER ATTORNEYS Feb. 15, 1966B. K. NASTER 3,

VOLTAGE REGULATORS Filed July 10. 1961 5 Sheets-Sheet 2 22 A FIG.4 INPUT1 P REG: OUTPUT $1 40 28 Cl 2o W 64 mf s2 3 INPUT OUTPUT S 5INPUTVOLTAGE 5} 2 2 INVENTOR. BERT K. NAsTER ATTORNEYS Feb. 15, 1966 B.K. NASTER 3,2 ,7

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VOLTAGE REGULATORS Filed July 10. 1961 5 Sheets-Sheet 5 INPUT REG.OUTPUT HVVENTUR. BERT K. NASTER ATTORNEYS United States Patent 3,235,789VOLTAGE REGULATORS Bert K. Naster, 3000 Taft Road, Hollywood, Fla. FiledJuly 10, 1961, Ser. No. 123,961 23 Claims. (Cl. 323-45) This is acontinuation-in-part of application Serial No. 783,335, filed December29, 1958, now abandoned.

This invention relates to voltage regulators of the type utilizing oneor more electromagnetic transformers.

One object of the present invention is to provide a new and improvedvoltage regulator requiring only one transformer having a plurality ofwindings.

A further object is to provide a new and improved voltage regulator ofthe foregoing character which affords excellent voltage regulation, yetis small, light in weight, and low in cost.

Another object is to provide a new and improved voltage regulator inwhich power is supplied to the output circuit not only by the regulatingtransformer but also by a resonant circuit containing a condenser, thecondenser current being a factor in the regulating action.

A further object is to provide a new and improved voltage regulator inwhich the regulating transformer is arranged so that some or all of thesecondary windings of the transformer will have a high leakagereactance.

Another object is to provide a new and improved voltage regulatorutilizing a single regulating transformer, plus a single auxiliarytransformer to correct the output wave form so that it will besubstantially a sine wave.

A further object is to provide a new and improved voltage regulatorarranged to provide a balanced three wire output circuit having tWo linewires and a neutral wire, the voltages between the line wires and theneutral wire being half the voltage between the two line wires.

Another object is to provide a new and improved voltage regulator of theforegoing character which may be arranged for use as a distributiontransformer, to step down a high input voltage to a relatively lowvoltage suitable for operation of household lamps and appliances.

Further objects and advantages of the present invention will appear fromthe following description, taken with the accompanying drawings, inwhich:

FIG. 1 is a schematic diagram showing a voltage regulator to bedescribed as an illustrative embodiment of the present invention.

FIG. 2 is a diagrammatic elevational view showing not only the circuitof the regulator but also the layout of the windings and the laminatedcore of the regulating transformer.

FIG. 3 is an end view of the regulating transformer shown in FIG. 2.

FIG. 4 is a schematic circuit diagram of the regulator, the view beingsimilar to FIG. 1 but rearranged to present certain aspects of theregulator with greater clarity.

FIG. 5 is a diagram showing oscillograms of the input and outputvoltages.

FIG. 6 is a vector diagram illustrating certain aspects of the operationof the regulator.

FIG. 7 is a schematic diagram showing a modified regulator adapted foruse as a distribution step-down transformer, the regulator having a waveform correction transformer to provide a substantially sine wave output.

FIG. 8 is a schematic diagram of another modified regulator, similar tothat of FIG. 7, but with the input circuit electrically isolated fromthe output circuit.

FIG. 9 is a schematic diagram of another modified regulator, similar tothat of FIG. 7, but arranged to provide a balanced three wire output.

FIG. 10 shows another modified regulator, similar to that of FIG. 8, butadapted to provide a balanced three wire output.

FIG. 11 shows still another modified regulator, somewhat similar to thatof FIG. 8 but again arranged to provide a balanced three wire output.

FIG. 12 illustrates a modified regulator similar to the regulator ofFIGS. 16 but of simplified construction.

It will be seen that the regulator 20 of FIGS 14 cmploys a singleregulating transformer T1 and a capacitor C1. The regulator 20 has inputleads 22 and 24 which may be connected to a source of alternatingcurrent at any suitable voltage and frequency, such, for example, asvolts and 60 cycles. The regulator supplies a regulated output voltageacross a pair of output leads 26 and 28. In this case, the output lead26 is connected directly to the input lead 22.

While the construction of the transformer T1 may be varied to aconsiderable extent, the illustrated transformer has a single primarywinding P1 and four secondary windings S1, S2, S3 and S4. All of thewindings are mounted on a magnetic core or lamination 30.

All of the windings of the transformer T1 may be Wound in the samedirection. In FIGS. 1 and 2, the starting end of each winding isindicated by St, while the finishing end is indicated by F.

It will be seen that the starting and finishing ends of the primary P1are connected to the input leads 22 and 24, respectively. The secondarywindings S1 and S3 are connected in series across the output leads 26and 28. However, the windings S1 and S3 are connected so that theirinduced voltages will buck each other. Thus, the starting end of S1 isconnected to the output lead 26, and also to the input lead 22. A lead32 is connected between the finishing end of S1 and the finishing end ofS3. It will be seen that the starting end of S3 is connected to theoutput lead 28.

All of the secondary windings S1S4 are employed to feed current throughthe condenser C1. Thus, S1, S3, S2, C1 and S4 are connected in seriesbetween the input leads 22 and 24. More specifically, a lead 34 extendsbetween the starting end of S3 and the finishing end of S2. The startingend of S2 is connected to one side of the condenser C1 by a lead 36. Theother side of the condenser Cl is connected to the starting end of S4 bya lead 38. A lead 40 extends between the finishing end of S4 and theinput lead 24. It will be understood that the condenser C1 may belocated elsewhere in the series circuit. Thus, it may be broken intoeither the lead 34 or the lead 40.

The physical layout of the transformer T1 is shown in in FIGS. 2 and 3.The illustrated lamination 30 comprises a single, straight elongated leg42 upon which all of the windings are mounted. To provide return pathsfor the magnetic flux, the core 30 includes a rectangular magneticmember 44 having four legs 46, 47, 48 and 49. It will be seen that thelegs 46 and 48 are parallel to each other and are relatively elongated.The legs 47 and 49 are relatively short and are connected between theopposite ends of the legs 44 and 48. As shown, the central leg 42extends between the end legs47 and 49 and is parallel to the side legs46 and 48.

In this case, the secondary winding S1 is closely coupled to the primaryP1, while the secondaries S2, S3 and S4 are loosely coupled to theprimary. Thus, the secondary S1 is immediately adjacent the primary P1.In fact, as shown in FIG. 3, it is wound over the primary P1. Thesecondaries S2, S3 and S4 are spaced from the primary P1, atsuccessively increasing distances. As shown in FIG. 2, these secondariesare arranged end to end. The secondary S4 is on the opposite end of thecentral leg 42 from the primary P1. The arrows on the 54 between the endof the central leg 42 and the end leg 47. Of course, the air gap may befilled with nonmagnetic material. As shown, the left-hand end of thecentral leg 42 has tapered or beveled corners 56 which are in localengagement with the end leg 47. However, the area of engagement is smallso as to maintain the high reluctance.

It will be noted that the air gap 54 is at the end of the central leg 42occupied by the primary P1. Accordingly, this air gap imparts leakagereactance to the secondaries S2, S3 and S4 and also, to some extent, tothe primary P1 4, value of microfarads. The following table gives thenumber of turns and wire size for each of the windings:

Winding Number Wire Gauge of Turns P1 340 24 S1 67 20 S2 170 18 S3 25518 S4 14 18 This regulator has sufficient capacity to operate atelevision receiver or other appliances. The voltage regulation of theoutput voltage is very good. Moreover, the input power factor is quitehigh. The output to input efiiciency of the regulator is also verysatisfactory. These facts are clearly shown by the following table,representing the results of a series of tests in which the input linevoltage was varied from 95 to 135 volts:

Input Input Output Input Line Input Input Volt- Power Output OutputOutput to Input Volts Amp Watts Amp Factor, Volts Amps Watts Etficiencypercent percent and the secondary S1. A butt joint 58 is formed betweenthe right-hand end of the central leg 42 and the end leg 49. Additionalleakage reactance is provided by magnetic shunts 60 and 62 which extendpart way between the side legs 46 and 48 and the central leg 42. Asshown, the shunts 60 and 62 take the form of projections on the sidelegs 46 and 48. Air gaps 64 and 66 are formed between the central leg 42and the shun-ts 60 and 62. It

will be seen that the shunts 60 and 62 are disposed between the primaryP1 and the secondary S2. Thus, the shunts impart considerable leakagereactance to the secondaries S2, S3 and S4. Of course, the leakage isgreater as to S3 and S4 than it is as to S2.

It will be noted that the secondaries S2 and S3 are Thus, the condensercurrent causes voltage drops in the reactances of the secondaries S1-S4.With changing input line voltage, the saturation of the core 30 changes.This changes the leakage reactances of the windings and thereforechanges the degree of resonance. All these factors are combined andbalanced to provide a regulated output over a wide range of inputvoltage.

Of course, the regulator may be constructed in various sizes to handlevarious voltages and deliver various amounts of power. ticular regulatorwill be of interest. This regulator was tested and was found to operatewith a high degree of satisfaction with an output of about 185 wattsatabout 120 volts, and an input ranging from about 100 volts to 135volts. This regulator employed a condenser having a This regulator alsohas the advantage that the output voltage rises very little if the loadis disconnected from the output. Thus, in one test, the output voltagewith a load of 175 watts was 120 volts, while the output voltage with noload was only 121 volts.

Moreover, the condenser current is kept down to a reasonable level at noload. The primary current decreases substantially when the load isremoved, so that the regulator does not overheat at no load. These factsare shown by the following table:

However, various details of a par- Primary Wire Current CapacitorCurrent Linc Volts Loaded, A. No Load, Loaded, A. N 0 Load,

FIG. 5 shows oscillograms 70 and 72 representing the wave forms of theinput and output voltages, respectively. Of course, the input wave formis substantially a sine wave. The output wave form shows some harmoniccontent, due to the action of the condenser C1. Moreover, the phase ofthe output voltage is displaced from that of the input voltage.

FIG. 6 shows a series of vector diagrams illustrating certain aspects ofthe operation of the regulator. Each of these diagrams shows the inputvoltage, the output voltage, and the vector difference between thevoltages. It has already been noted that the output voltage is thevector sum of the voltages across S1 and S3. The vector differencebetween output and input voltages is equal to! the vector sum of thevoltages across C1, S2 and S4. FIG. 6 shows successive vector diagramsfor input voltages of 75, 85, 95, 105, 115, 125 and 135. It will be seenthat the vector representing C1 plus S2 plus S4 increases;

,75 substantially in length with increasing input voltage...

However, the phase of this vector changes considerably. This change inphase compensates for the change in magnitude, so that the magnitude ofthe output voltage remains substantially constant. Of course, the phaseof the output voltage changes to a considerable extent.

It has already been indicated that the output of the regulator is takenacross the secondaries S1 and S3. These windings are so phased that S1bucks S3. In the illustrated regulator, S3 has nearly four times as manyturns as S1. With a regulated output voltage of 118 volts, S3 maydeliver 140 volts, while S1 is delivering 40 volts. The regulated outputvoltage is substantially greater than the simple difference (100 volts),because the voltages across S1 and S3 are somewhat less than 180 degreesout of phase. The relative phasing of the voltages across S1 and S3changes with various values of input voltage to maintain the regulatedoutput voltage at a substantially constant value. This phase shiftingaction is due to the condenser current and. the inductive reactances ofthe secondary coils in the condenser circuit. S1 acts as a buckingwinding at high input voltages and as an aiding winding at low inputvoltages. Thus, the action of S1 improves the regulation by pushing upthe output voltage at low input voltages and by holding down the outputvoltage at high input voltages.

The bucking action of the secondary coils S1 and S4 is an importantfactor in limiting the condenser current at high values of inputvoltage. The secondary S1 is closely coupled to the primary P1, so thatthe bucking action of S1 is particularly pronounced. The loose couplingbetween the primary and S2, S3 and S4 also contributes to thestabilizing of the condenser current and the maintenance of asubstantially constant output voltage. The provision of S4 makes itpossible to reduce the value of C1 so that Cl will be physicallysmaller.

The arrangement of the secondary coils S1-S4 also provides output waveform correction, so as to minimize the departure of the output wave formfrom a sine wave. The bucking action of the coils S1 and S4 contributesto the improvement in wave form by limiting the condenser current athigh values of input voltage. The inductive reactances of the secondarycoils also improves the wave form. Still further correction of the waveform may be achieved by tapping down the lead 40 on the primary P1. Thisloosens the coupling between the input and the condenser circuit andalso tends to improve the efliciency of the regulator.

The lamination or core 30 is of the two window type. Thus, the shunts 60divide the opening in the rectangular core member 44 into two portionsor windows 80 and 82. The primary P1 and the secondary S1 are disposedin the window 80. These windings may be wound in one operation as onecoil unit 84. The secondaries S2, S3 and S4 are disposed in the secondwindow 82. Here again, these coils may be wound in one operation as asecond coil unit 86. Thus, the provision of only two windows simplifiesthe winding of the coils, so that only two basic coil units are needed.

The series circuit comprising the coils S1, S2, S3 and S4 and thecondenser C1 is energized directly from the input leads 22 and 24.Accordingly, current flows in this series resonant circuit, even Withoutthe aid of the primary P1. Thus, in a real sense, the circuit comprisingS1, S2, S3 and S4 constitutes a second. primary circuit. Additionalinductive excitation is provided by the primary P1. As already noted,the primary P1 is quite loosely coupled to S2, S3 and S4. While theexcitation afforded by the primary furnishes a high degree of regulationin the output voltage, the primary handles only a portion of the powerdelivered to the output circuit. Thus, the primary losses and thetransformer losses are minimized. This improves the efiiciency of theregulator and reduces the heat generated therein. This factor alsominimizes the amount of core material and wire that must be employed inthe transformer. Accordingly, the size, Weight and cost of thetransformer are reduced. The direct coupling of the secondary coils tothe input also provides faster response time, so that the regulatorquickly accommodates itself to abrupt changes in input voltage.

The regulator provides excellent voltage regulation under a variety ofload conditions. Thus, various appliances having different powerrequirements may be operated by the regulator. Even at no load, theoutput voltage of the regulator rises only slightly from the full loadvalue.

If the output of the regulator is accidentally short circuited, theregulator is thrown out of resonance, so that the output current doesnot increase excessively. This protects both the regulator and theappliance from damage. The power input to the regulator actually isreduced wtih a short-circuited output.

As already indicated, the regulator maybe arranged to operate at anyinput voltage and frequency, and at any output voltage. S2 and S3 mayconstitute a single winding with a tap thereon. The output voltage maybe varied by changing the position of the tap. In effect, the lead 34constitutes a tap between S2 and S3. This tap may be moved to anydesired point on these windings.

Two or more of these regulators may be connected in parallel to increasethe load capacity. The total load capacity is equal to the sum of theindividual load capacities of the regulators. The regulators areconnected in parallel simply by connecting the corresponding input andoutput leads together. Of course, the leads must be properly phased. Theregulators may also be connected in various two-phase, three-phase orpolyphase arrangements.

FIG. 7 illustrates a somewhat modified regulator which will bedesignated 20-7. Except as indicated below, this regulator may be thesame as FIGS. 1-3. Corresponding components of the regulators 20 and20-7 have been given the same reference characters.

The regulator 20-7 differs from the regulator 20 in two principalrespects. First, the regulator 20-7 is adapted to step-down a high inputvoltage to a relatively low output voltage. Thus, the regulator may beemployed as a distribution transformer. The input voltage may be anysuitable value, such as 2300, 13,000, or the like. The output may be the120 volts, 230 volts, or any other suitable value. The regulator isadapted for use as a distribution transformer by providing a slightlymodified regulating transformer T1-7. This transformer differs from thetransformer T1 in that it has a high voltage primary winding P1-7. Asbefore, the starting end of S1 is connected to the starting end of P1-7.H-ow ever, the primary P1-7 has a tap which is employed to excite thecondenser circuit, so that only a portion of the input voltage isapplied to the condenser circuit.

The second difference between the regulators 20-7 and 20 resides in thefact that the regulator 20-7 is provided with a second transformer T2adapted to correct the wave form of the output voltage, so that theoutput wave form will be substantially a sine wave. The illustratedtransformer T2 has a primary P2 and one secondary S5, both of which arewound on a magnetic core 92. It will be seen that the core 92 has amagnetic shunt 94 between the primary P2 and the secondary S5, so thatthe secondary will be loosely coupled to the primary. Thus, both theprimary and the secondary have substantial leakage reactances.

In order to minimize harmonic current through the condenser C1, thesecondary S5 is connected in series with the condenser circuit. In thiscase, the finishing end of S4 is connected to one end of S5 by a lead96. The other end of S5 is connected to the primary tap 90 by a lead 98.It will be understood that S5 might be connected elsewhere in the seriescondenser circuit. The inductive reactance of S5 reduces the harmoniccontent of the condenser current, and thus improves the output Waveform.

It will be seen that the primary P2 is connected directly between theoutput leads 26 and 28. The harmonic content in the output voltage isthus fed back into the condenser circuit, by the electromagnetictransforming action between P2 and S5. The feed back is phased so as tobe negative or out of phase. In this way, the harmonic content in theoutput voltage and the harmonic component of the condenser currentcancel or buck each other. Thus, the provision of the transformer T2results in an output wave form which is substantially sinusoidal. Thesine wave output makes the regulator 20-7 particularly applicable as adistribution transformer.

FIG. 8 illustrates another modified regulator 20-8 which is similar inmost respects to the regulator of FIG. 7. The principal differencebetween the regulators. 20-8 and 20-7 resides in the fact that theregulator 20-8 has a slightly modified regulating transformer T1-8 witha primary winding P1-8 which is isolated or floating, with respect tothe output leads 26 and 28. Thus, there is no electrical connectionbetween the input leads 22 and 24 and the output leads 26 and 28. Theinput leads 22 and 24 are simply connected across the primary Pl-S. Thisarrangement contributes an additional safety factor, in that the inputcircuit, which may be at a high voltage, is not electrically connectedto the output circuit. Thus, the transformer may be arranged tostep-down an extremely high voltage, such as 2300 or 13,000 volts, to arelatively low voltage, such as 115 or 230 volts.

In the regulator 20-8, the lead 98 is replaced with a lead 98a, toconnect the right-hand end of the secondary S to the starting end of S1.A lead 981: runs from the lead 98a to the output lead 26. Thus, theleads 98a and 98b complete the output circuit and the condenser circuit.In this case, the condenser circuit is energized entirely by thevoltages induced in the secondaries S2 and S3. The action of the buckingsecondaries S1 and S4 is the same as previously described.

FIG. 9 illustrates a modified regulator 20-9, which is the same as theregulator 20-7, except for modifications to provide a balancedthree-wire output. In general, the balanced output is obtained byproviding an additional set of regulator components connected in thesame manner as the original set. The output of the additional regulatorcomponents is connected additively in series with the output of theoriginal components. The two outputs share one lead in common, toprovide a center tap or neutral wire.

In the regulator 20-9, the output lead 26 is shared to provide theneutral wire. The output lead 28 is replaced with two leads 28a and 28bdelivering voltages which are balanced with respect to the neutral lead26.

The regulator 20-9 has a somewhat modified regulation transformer Til-9,which is provided with two sets of secondary windings. Each setcomprises four secondaries, as before. The secondaries of the first setare designated Slla, 52a, S342 and 84a. Similarly, the secondaries ofthe second set are designated S1b, S219, S312 and 841:. It will be seenthat the starting end of SM is connected to the finishing end of S111,and also to the input lead 22, as in FIG. 7. In this case, twocondensers Cla and C112 are provided. The regulator 20-9 has a somewhatmodified correction transformer T2-9 having two primaries P2a and P212and two secondaries S5a and S517. It will be seen that the primary P2ais connected between the leads 28a and 26, while the primary P212 isconnected between the leads 26 and 20b. As shown, the windings P211 andP212 may actually comprise a single cent-er tapped winding, the neutrallead 26 being connected to the center tap 102. The neutral lead 26 isalso connected to the input lead 22 and the starting end of 81a, asbefore.

The transformer T1-9 has a somewhat modified primary winding P1-9. Inthis case, the input lead 22 is connected to a tap 900 near the startingend of the primary P1-9. This tap 90c serves, in effect, as a center tapbetween the starting end 90b and another tap 90a, spaced up the windingP-9 from the tap 900. The resonant circuits for the condensers CM andC117 have return leads 98a and 9812 which are connected to the coil tapsor terminals 90a and 9012. With this arrangement, oppositely phasedvoltages, derived from the primary winding P1-9, are fed into thecircuits for the condensers Cla and C11).

The secondaries Sla, S311, S211, S411 and a and the condenser Cla areconnected much the same as the corresponding components in FIG. 7. Thisis also true of the components S112, S312, S211, S4b, S51) and C112,except the polarities of all windings are reversed. Thus, thesecondaries S111 and 53a are connected in a bucking series circuitbetween the leads 26 and 28a. Likewise, the second.- aries Slb and S312are connected in a bucking series circuit between the leads 26 and 28b.

All of the secondaries Sla, 53a, S2a, 85a, and 84a are connected inseries with the condenser Cla between the primary terminals 900 and a.In this case, the condenser Cla is disposed in the series circuitbetween the windings S4a and 85a. The windings Slb through S5b aresimilarly connected in series with the condenser Clb across the primaryterminals 900 and 90b.

It will be appreciated that the input lead 22 could be connected to theend lead 90b, but the illustrated arrangement has the advantage ofpermitting both the input lead 22 and the neutral output lead 26 to begrounded. With the illustrated arrangement, equal but oppositely phasedvoltages appear between the leads 28a and 28b and the neutral 26. Thevoltage between the leads 28a and 28b is twice the voltage betweeneither lead and the neutral.

FIG. 10 illustrates another modified regulator 20-10 which is similar tothe regulator 20-9 of FIG. 9, except that the primary arrangement issimilar to that of the regulator 20-8 of FIG. 8. Thus, the regulator20-10 employs a regulating transformer T1-10 with a primary P1-8 whichis the same as described in connection with FIG. 8. The input leads 22and 24 are connected across the primary 1 1-8, but are entirely isolatedfrom the output leads 26, 28a and 28b. In this case, the neutral outputlead 26 is connected directly to the ends of the secondaries SM and Slbby a lead 106. A lead 108 runs between the output lead 26 and the endsof the secondaries S-4a and S417. It will be noted that the leads 106and 108 connect the ends of the secondaries Sla and S1]; to the ends ofthe secondaries 84a and S412. Otherwise, the regulator circuit is thesame as described in connection with FIG. 9.

It will be noted that the secondaries Sla and Slb of FIG. 10 may beformed as a single center tapped winding. This is also true of thesecondaries 54a and 54b. The secondaries 52a and S311 may he wound as asingle tapped coil. The same is true of the secondaries S21) and S312.

FIG. 11 illustrates still another modified regulator 20-11 which alsoprovides a "balanced three-wire output across leads 26, 28a and 28b. Theregulator 20-11 actually comprises two regulators of the type shown inFIG. 8. In FIG. 11, the regulators are designated 20-812 and 20-8b. Inthis case, the inputs of the regulators are connected in parallel, whilethe outputs are connected additively in series. The output lead 26 isshared by both regulators to form a neutral which may be grounded.

In all of the regulators, the fourth secondary S4 of the regulatingtransformer may be omitted in many cases. The leads that would run tothese windings are then simply connected together. Omission of thiswinding tends to increase the capacitor current and voltage at higclilinput voltages, but in some cases this can be tolerate FIG. 12illustrates a simplified voltage regulator which is somewhat similar totheregulator 20 of FIG. 1.

9 However, both S1 and S4 have been omitted. Moreover, S2 and S3 havebeen combined to form a single secondary S, having a tap 122,corresponding to the lead 34 between the secondaries S2 and S3 inFIG. 1. The portions of the secondary S corresponding to S2 and S3 havebeen designated as S2 and S3 in FIG. 12.

The regulator 120 has a primary winding P which corresponds to theprimary P1 of FIG. 1, except that the primary P may have a tap 124. Itwill be seen that the input leads 22 and 24 are connected directlyacross the primary P. The output leads 26 and 28 are connected acrossthe coil S3, constituting a portion of the secondary winding S. It willbe understood that the output may be connected across all or any portionof the secondary S, depending upon the desired output voltage.

The resonant series circuit comprising the capacitor C1 and thesecondary winding S may be connected directly across the input, but, inthe arrangement of FIG. 12, this resonant circuit is connected to thetap 124 and thus is connected to only a portion of the primary windingP. Thus, a series circuit may be traced from the tap 124 through thecapacitor C1 and the secondary winding S to the input lead 22. Thisseries circuit is connected across the portion of the primary winding Pbetween the tap 124 and the input lead 22.

It will be understood that the portion of the input voltage between thetap 124 and the lead 22 produces current through the series circuitcomprising the capacitor C1 and the secondary winding S. Additionalexcitation is supplied to the secondary S by virtue of the inductivecoupling between the primary winding P and the secondary S. Due to thespacing between the primary P and the secondary S, and also due to theprovision of the magnetic shunt 6d, the coupling between the primary Pand the secondary S is quite loose. Thus, the secondary S has a highleakage reactance. The combined effect of the capacitive coupling andthe loose inductive coupling produces the voltage regulating effect, sothat very little change in the output voltage occurs, even when theinput voltage across the leads 22 and 24 varies widely.

Only a portion of the energy is transmitted to the output circuit by thetransformer T12, comprising the primary P and the secondary S. Theremaining portion of the energy is transmitted by the capacitor C1.Thus, the transformer T12 may be made with a smaller amount ofmaterials, both copper and iron, than would normally be the case.Moreover, the losses in the transformer are relatively low. Thus, theregulator is efficient in operation and low in cost.

The capacitor current through the secondary S is phased in such a mannerthat the magnetic flux produced by the capacitor current tends to opposethe flux produced by the primary winding. This action reduces the totalmagnetic flux in the iron core 30 so that a relatively small core may beemployed.

If the output is accidentally short-circuited, this merely has theeffect of short-circuiting S3, which is only a portion of the secondaryS. Due to the high leakage reactance of S3, the short-circuited currentthrough S3 is quite low. Moreover, the short-circuiting of S3 throws theseries circuit, comprising the capacitor C1 and the secondary S, out ofresonance so that the input current to the regulator does not increaseappreciably and may actually decrease.

Although the winding S has generally been referred to as a secondary, itconstitutes, in a real sense, a second primary, fed directly from theinput by the condenser C. Current will flow through the series circuit,comprising C and S, independently of the induced excitation from thewinding P.

By moving the tap 122, the output may be connected across all or anyportion of the winding S. This will change the output voltage.

By moving the tap 124, the series resonant circuit, comprising C1 and S,may be connected across all or any portion of the winding P. Tappingdown this series circuit on the primary P loosens the coupling betweenthe input and the series circuit and tends to improve the Wave form ofthe output voltage, as well as improving the efliciency of theregulator. The regulator may provide either a voltage step-down or avoltage step-up, according to the positions of the taps 122 and 124, andthe number of turns in the windings.

It will be evident that the regulators of the present invention provideexcellent voltage regulation, yet are remarkably simple, small in size,light in weight and low in cost. The regulators operate with a highdegree of efiiciency. The regulated output voltage is maintained with ahigh degree of accuracy, despite wide variations in the input voltageand the load. The regulators may be arranged to deliver a substantiallysinusoidal output.

Various other modifications, alternative constructions and equivalentsmay be employed without departing from the true spirit and scope of theinvention, as exemplified in the foregoing description, and defined inthe following claims.

I claim:

1. In a voltage regulator, the combination comprising a transformerhaving a magnetic core, a primary winding and first, second, third andfourth secondary windings on said core, said first secondary Windingbeing adjacent and closely coupled to said primary winding, said second,third and fourth secondary windings being spaced along said coresuccessively farther from said primary winding, said core having amagnetic shunt disposed between said primary winding and said second,third, and fourth secondary windings to afford loose coupling betweensaid primary winding and such secondary windings while imparting highleakage reactance to such secondary windings, first and second inputleads connected across said primary winding, first and second outputleads, an output circuit connecting said first and third secondarywindings in series across said output leads, said first secondarywinding being phased to buck said third secondary winding, a resonatingcondenser, a condenser circuit connecting all of said secondary windingsin series with said condenser, said second and third secondary windingsbeing phased to aid each other, said first and fourth secondary windingsbeing phased to buck said second and third secondary windings in saidcondenser circuit.

2. The combination of claim 1, with a second transformer having asecondary winding connected in series with said condenser circuit toreduce harmonic current therein, said second transformer having a secondmagnetic core, said secondary winding of said second transformer beingmounted on said core, a secondary primary winding mounted on said coreand connected across said output leads to feed back harmonics from saidoutput leads to said condenser circuit and thereby effect mutualcancellation of the harmonic content in the output voltage and thecondenser current, said second core having a magnetic shunt disposedbetween said second primary winding and said secondary winding of saidsecond transformer.

3. The combination of claim 1, with a second similar regulator havinginput leads connected in parallel with the input leads of the firstregulator, said second regulator having one output lead shared in commonwith said first regulator, and an additional output lead to provide abalanced three-wire output, said second regulator having its outputcircuit connected additively in series with the output circuit of thefirst regulator.

4. In a voltage regulator, the combination comprising a regulatortransformer having a magnetic core, a primary winding and four secondarywindings mounted on said core, said core having magnetic shunt meansimparting inductive reactance to at least some of said secondarywindings, first and second input leads connected across said primarywinding, first and second output leads, an output circuit connecting twoof said secondary windings in series across said output leads, one ofthe secondary windings in said output circuit being phased to buck theother, a condenser, and a condenser circuit connecting all of saidsecondary windings in series with said condenser to provide circulatingcurrent in said condenser circuit, two of the secondary windings in saidcondenser circuit being phased to buck the other two secondary windings.

5. The combination of claim 4, with a second transformer comprising amagnetic core having a second primary winding and an additionalsecondary winding thereon, said additional secondary winding beingconnected in series with said condenser circuit, said second primarywinding being connected across said output leads to effect mutualcancellation of the harmonic content in the output voltage and thecondenser current.

6. The combination of claim 4, with a second similar regulator havingits input leads connected in parallel with the input leads of the firstregulator, and the output leads of the second regulator connectedadditively in series with the output leads of the first regulator, oneoutput lead thereby being shared by both regulators to provide abalanced three-wire output.

7. The combination of claim 4, in which said primary winding is providedwith a tap, and in which said condenser circuit includes the portion ofsaid primary Winding between said tap and one end thereof.

8. The combination of claim 4, in which said input leads are connectedin series with said condenser circuit.

9. The combination of claim 4, with four additional secondary windingson said core, each of said additional windings corresponding to one ofsaid first mentioned four windings, an additional condenser, anadditional pair of output leads, and means connecting said additionalsecondary windings with said additional condenser and said additionaloutput leads in the same manner as said first mentioned secondarywindings, condenser and output leads, said additional output leads beingconnected additively in series with said first mentioned output leads toprovide a balanced three-wire output.

10. In a voltage regulator, the combination comprising a transformerhaving a magnetic core, a primary Winding and a plurality of secondarywindings mounted on said core, at least one of said secondary windingsbeing loosely coupled to said primary winding to impart inductivereactance to such secondary windings, an circuit connected to saidprimary winding, a pair of output leads, an output circuit connectingtwo of said secondary windings in series across said output leads, saidsecondary windings in said ouput cidcuit being phased to buck eachother, a condenser, and a condenser circuit connecting all of saidsecondary windings in series with said condenser, at least one of thesecondary windings in said condenser circuit being phased to buck theother windings.

11. The combination of claim 10, in which said condenser circuitincludes at least a portion of said primary winding.

12. The combination of claim 10, in which said input circuit isconnected in series with said condenser circuit.

13. The combination of claim 10, with a second trans former including asecond magnetic core having a second primary winding and an additionalsecondary winding thereon, said additional secondary winding beingconnected in said condenser circuit, said second primary winding behindconnected to said output circuit to effect mutual cancellation ofharmonics in said output circuit and said condenser circuit.

14. The combination of claim 10, with additional similar regulatorcomponents having output leads connected additively in series with theoutput leads of the first regulator to provide a balanced three-wireoutput.

15. In a voltage regulator, the combination comprising a transformerhaving a magnetic core, a primary winding and four secondary windingsmounted on said core, said core having magnetic shunt means impartinginductive reactance to at least some of said secondary windings, firstand second input leads connected across said primary winding, first andsecond output leads, an output circuit connecting two of said secondarywindings in series across said output leads, one of said secondarywindings in said output circuit being phased to buck the other, acondenser, and a condenser circuit connecting at least a portion of saidprimary winding and all of said secondary windings in series with saidcondenser to provide circulating current in said condenser circuit, twoof said secondary windings in said condenser circuit being phased tobuck the other two secondary windings.

16. In a voltage regulator, the combination comprising a transformerhaving a magnetic core, a first winding on a first portion of said core,a second winding on a second portion of said core and loosely coupled tosaid first Winding, input means for producing a voltage across saidfirst winding, a capacitor, a closed circuit connecting said capacitorand said second winding in series with at least a portion of said firstwinding to form a closed loop, and an output circuit connected to atleast a portion of said second winding.

17. The combination of claim 16, in which said input means comprise aninput circuit connected across at least a portion of said first winding.

18. The combination of claim 16 in which said input means comprise aninput winding on said first portion of said magnetic core and closelycoupled tosaid first winding.

19. The combination of claim 16, including a magnetic shunt between saidfirst and second windings to loosen the coupling therebetween.

20. In a voltage regulator, the combination comprising a transformerhaving a magnetic core, a primary winding on said core, a pair of inputterminals connected across said primary winding, a secondary winding onsaid core and loosely coupled to said primary winding, a capacitor, acircuit connecting said capacitor and said secondary winding in seriesacross said primary winding to form a closed loop therewith, saidprimary and secondary windings being additively phased around said loop,and a pair of output terminals connected across at least a portion ofsaid secondary winding.

21. In a voltage regulator, the combination comprising a transformerhaving a magnetic core, a first winding on a first portion of said core,a second winding on a second portion of said core and loosely coupled tosaid first winding, input means for producing a voltage across saidfirst winding, a capacitor, and a closed circuit connecting saidcapacitor and said second winding in series with at least a portion ofsaid first winding to form a closed loop.

22. In a voltage regulator, the combination comprising a transformerhaving a magnetic core, a first winding on a first portion of said core,a second winding on a second portion of said core and loosely coupled tosaid first winding, input means for producing a voltage across saidfirst winding, a capacitor, a closed circuit connecting said capacitorand said second winding in series with at least a portion of said firstwinding to form a closed loop, and means for deriving an output voltagefrom said second winding.

23. In a voltage regulator, the combination comprising a transformerhaving a magnetic core, a first winding on a first portion of said core,a second winding on a second portion of said core and loosely coupled tosaid first winding, input means for producing a voltage across saidfirst winding, a capacitor, a closed circuit connecting said capacitorand said second winding in series with at least a portion of said firstwinding to form a closed loop, and output means for deriving an outputvoltage from said transformer.

References Cited by the Examiner 4/1951 Bridges 32360 X Sola 32360Feinberg 323-45 X Hjermstad et a1. 32360 X Sola 323-61 Strecker 315278LLOYD MCCOLLUM, Primary Examiner. ROBERT C. SIMS, Examiner.

21. IN A VOLTAGE REGULATOR, THE COMBINATION COMPRISING A TRANSFORMERHAVING A MAGNETIC CORE, A FIRST WINDING ON A FIRST PORTION OF SAID CORE,A SECOND WINDING ON A SECOND PORTION OF SAID CORE AND LOOSELY COUPLED TOSAID FIRST WINDING, INPUT MEANS FOR PRODUCING A VOLTAGE ACROSS SAIDFIRST WINDING, A CAPACITOR, AND A CLOSED CIRCUIT CONNECTING SAIDCAPACITOR AND SAID SECOND WINDING IN SERIES WITH AT LEAST A PORTION OFSAID FIRST WINDING TO FORM A CLOSED LOOP.